Wind brake for aircraft



Much 22,1938. P. v. D'oE-PP 2,111,889

WIND BRAKE FOR AIRCRAFT Original Filed 'Ju e 29, 1934 Jamey/02. @60 1 w, M -*6 l z t e Patented Mar. 22, 1938 WIND BRAKE FOR AIRCRAFT Philipp w. Doepp, Dessau, Germany, assignor to Junkers Flugzeug-und-Motorenwerke Aktiengesellschaft, Dessau, Germany Original application June 29, 1934, Serial No.

many July 3, 1933 This application is a division of -my pending application for patent of the United States Serial No. 733,136 for Brakes for aircraft", filed June 29, 1934.

It relates to a modification of the wind brake described and claimed in the main application and it is an object of the present invention to provide means whereby the wind brake can be adjusted more readily and with the expenditure ofless force.

Wind brakes have been provided in connection with aircraft and more especially flying machines, these brakes having the form of ledges serving to, break up the air current formed above and/or below the surface of the wing. More particularly such ledges have been provided for breaking up the air current at the underside of the wing and provision has been made for bringing such ledges into operative position by rocking them about their axle.

-Wind brakes of the kind above mentioned involve the drawback that theledges must be rocked into operative and inoperative position in a a direction opposed to the direction of flow of the wind, whereby a considerable expenditure of power is required to effect this movement.

The present invention now relates to a wind brake consisting of ledges secured to the wing for rocking motion, which requires only little power for adjustment. To this end I provide a pair of coacting ledges, each ledge being adjustable in a direction opposite to that of the other ledge, and I couple the ledges of the pair in such manner, that the air forces acting on them partly or altogether compensate each other. A wind brake of this kind canbe adjusted into and out of operative position either manually or automatically under the action of static pressure. I arrange these ledges about flush with the underside of the wing and near the front edge thereof and spaced from this edge not more than forty per cent of the chord length of the wing, one ledge extending on each side of the plane of symmetry and transversely to the direc tion of flight across a considerable part of the span of the wing. The ledges are hingedly connected to the wing. The axes about which they can be rocked, are so located relative to their edges, that in their inoperative position the free edge of .one ledge is disposed in front, the free edge of the other ledge" to the rear of its axis of rotation. I provide means for simultaneously rocking both ledges about their axes in opposite senses.

In a preferred embodiment of my invention I Divided and this application September 21, 1936, Serial No. 101,816.

In Gerposition wherethey are capable of breaking up W the air current in contact with the wing.

In the drawing aflixed to this specification and forming part thereof, two forms of a wind brake embodying my invention are illustrated diagrammatically by way of example.

In the drawin I Fig. 1 is a perspective view of a pair of ledges with means for adjusting same manually, while Fig. 2 is a similar view of a wind brake with means for automatic adjustment of same.

Fig. 3 is a diagrammatic showing of the arrangement of the brake of Fig. 2 in an airplane.

Referring to the drawing and first to Fig. 1, I and la are the two ledges serving to break up the air current on the underside of the wing and 2, 2a are the axles on which the ledges are fixed for rocking movement. The axles 2, 2a are arranged in staggered relation and toothed wheels 3, 3a gearing with each other'are mountedthereon. 4 is a hand lever fixed to the axle 21:.

Obviously if the axle 2a is turned by aid of motion about a pivot iii, an extension if: being acted uponby a spring II, which tends to counteract thestatic pressure acting on the surface 9.

If the pressure acting on this surface is low, in other words, if the craft is travelling at low speed, the two ledges 5, 5a are held in their in-- operative position by the action of spring ll.

With-increasing speed and wind pressure acting on the surface 9, this surface will be adjusted to approach a horizontal position, whereby the two ledges 5, 5a are adjusted into a position,

where they are capable of breaking up the air current in contact with the wing. ,I'his adjustment of the ledges requires little expenditure'of power, since the wind pressure acting on one ledge substantially balances the wind pressure acting on the other ledge.

I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described for obvious modification will occur to a person skilled in the art.

I claim:-

i, In an aircraft in combination, a wing or supporting plane, a pair of ledges arranged at the underside of said wing and extending substantially transversely to the-direction of flight and spaced from the front edge of said wing by a distance not exceeding forty per cent of the chord length of said wing, one ledge being arranged on either side of the plane of symmetry of the craft, the axes of rotation of said ledges being so arranged that in the inoperative position, in which the ledges lie about flush with the underside of the wing, the free edge of one ledge is disposed in front, the free edge of the other ledge to the rear of its axis of rotation, and means aliases for couplingsaid ledges for simultaneous rocking movement in relatively opposite sense.

2. 'li'hecombination of claim 1, in which the free edges of the ledges are spaced, in the operative position of the ledges, from the underside of said wing not more than six per cent of the chord length of said wing.

23. The combination of claim 1, in which means,

adjustable by the wind pressure, are associated with one of said ledges for automatically rocking same into and out of operative position.

4. The combination of claim 1, in which a toothed wheel coupling is provided to couple said 

